Are you sure we run the same? Maybe I lied to you..... The guys in Houston were smart enough to check my tires when thought I was pulling their legs, I felt so violated.

 

yeah, but we weren't smart enough to drop your pressures 15 psi during competition...

 

Lie to me? Why would you do that?

I thought we had this tire pressure discussion a few months ago.

 

Yeah.

 

OHHH....Evil "PUSH"...nm...I thought someone called...

 

it all depends on how accurate/calibrated your gauge is too, seen a lot of error over the years by people who never think to have them checked

 

Totally guilty of not recalibrating anything when it should be...and then kicking myself later for it...

 

We were also smart enough to check our gauges against Jason's, so his pressures didn't end up being as far off from what we run as they first sounded...

 

Well....we're waiting...let's hear the story, already

 

I think I was 6 psi higher than them.

 

you still doing that

https://www.rx8club.com/showpost.php...&postcount=141

 

No, this is my good gauge it is only off 2 lbs.

 

So, the moral to the story:

Whether your pressure gauge is accurate doesn't matter...as long as it's consistent. Don't pay attention to what other drivers' pressures are, they may or may not be relevant. Determine your own pressures, using your own gauge, using the normal indicators: roll over measured, pyrometer, lap times and what "feels" right to you (this is the one that gets many in to trouble!)

 

Very true.... Last year the I gauge that I have used for the last 10 years did not make it to natls, that could have been bad.

However when we used the same gauge to compare the guys in TX were 6 psi to low imho.

 

So, share the numbers...6 psi too low, comparing what to what on what type of surface?

 

LOL, how soon they forget ....




.

 

I know what you're getting at, but am still interested in knowing why ULLLLLLLLLLLLLLLLLLLLLLOSE was saying the TX guys were 6 psi too low (on the same gauge)...which begs the question as to what kind of pressures we're talking about. Even with a 2 psi "noise" margin, for different gauge calibration, its interesting data....

 

I was at 40psi.

 

So, they were running 34 psi front, Kumho 245, on asphalt? Was the K-U-M-H-O lettering wearing off, from rollover?

JK, but it would be interesting to see the wear pattern being created. I was getting pretty significant roll over (like past the edge of the tread surface limit strip) at 37 psi front, on asphalt, before taking my fronts up to 39-40 psi...at which level I'm using most all of the tire, while still allowing about a 1/16 to 1/8" "chicken strip". That's with a full -1.7 front camber.

 

full? LOL ... sounds like a partial to me ...

 

OK, bad choice of words.

You did get my point though?

 

I've got one tire that's got a little lettering worn off, but that's from a massive, smoky spin at about 75 mph at a local marque club event.

Seriously though, we typically run in the low 30s on asphalt. We wear the tires right out to the edge, but under normal conditions (i.e., not spinning) we wear them right to the edge but no further. That's with -1.6 front camber.

We really haven't had a good opportunity since Houston to take some time and test, but we did a few test days last season in Jon's car on a surface similar to HPT and found that we both ran faster times with lower pressures.

 

Wow. Does sound low. Did your better times with the lower pressures happen in the first few runs, or the last few runs? Are you able to be 99.9% consistent in driving to know that your better times were not a reflection of some other factor(s)?

Mark did some pressure tweaking for me at our last regional event, and imo the rear pressure changes (+/- 2 lbs.) were even more noticeable in handling than the fronts. Of course, that was on that course, that day, in those temps, in that direction. Too many variables.....

 

On our 18x8 rims and 245 Kumho's(on the Solstice though) we stay in between 33-35psi. That is the "fastest" pressures with our current setups according to our testing. We use Longacre digital gauges that self zero everytime you turn them that seem to be very accurate.
FM

 

Yeah, we use rear pressure changes to tweak the handling of the car for particular courses/surfaces (we have five distinctly different local surfaces). However, changing the f/r pressure differential by 2lbs isn't the same as upping your baseline pressure at all four corners by 2lbs, or even by 4lbs for that matter.

BTW, you don't need to worry about my testing protocol or familiarity with tire grip characteristics - I'm an engineer by trade, and I spent far too many late night hours during college doing tire testing for Dr. Wood's Formula SAE team (I'm a UTA alum).

I guess I'm trying to understand why everyone seems to want to run so much pressure in their tires. I could see using 40psi if I were trying to pinch a 225/50-15 on a 6" wide wheel like I used to do with my Miata (where you've got a tall sidewall tire on a wheel that's too narrow), but the 245/35-18 V710 on an 8" wide wheel is pretty well supported. After all, we're not getting any rollover at the pressures we use, and it's not like a 35-Series sidewall V710 needs high pressures to compensate for a tall or soft sidewall.